(Adds text message from USW, paragraph 4)
By Erwin Seba
HOUSTON, Feb 4 (Reuters) - The United Steelworkers union(USW) said a new contract offer was made by lead oil companynegotiator Royal Dutch Shell Plc on Wednesday night asa strike by U.S. refinery workers ended its fourth day.
"The USW has received an offer and will respond afterconsideration of the offer tomorrow," USW spokeswoman LynneHancock said. "I don't know what time they will considerit. Contents of the offer will not be revealed."
About 4,000 workers at nine plants, including sevenrefineries accounting for 10 percent of U.S. refining capacity,continue to walk picket lines in California, Kentucky and Texas.
In a text message to members seen by news media late onWednesday, the USW said: "minimal progress today."
Asked about the offer, a Shell spokesman simply said the twosides had continued negotiations on Wednesday.
The two camps have been in a stalemate since the USW calledwalkouts early on Sunday, saying Shell had left the negotiatingtable when talks broke down.
The talks have been tougher than in years past. A drop ofmore than 50 percent in oil prices since June has eroded profitsat major oil companies, prompting executives to say they cannotafford to lift wages for workers.
Further walkouts may be ordered at some of the otherrefineries and chemical plants the USW represents if there is noprogress in the talks, the union has said.
The union represents a total of 63 refineries accounting fortwo-thirds of national crude oil refining capacity.
LEAKS REPORTED
Also on Wednesday, two of the refineries affected by thestrike, Tesoro Corp's Los Angeles-area refinery inCarson, California, and Marathon Petroleum Corp's Galveston Bay Refinery in Texas City, Texas, reported leaks toregulators.
A Marathon spokesman said emergency responders in Texas Citywere notified of the leak as a precaution.
Marathon Chief Executive Gary Heminger, whose company ownstwo of the refineries where workers are on strike, deferred toShell as the lead negotiator regarding any comment, calling thetalks a "delicate situation."
Since bargaining first started on Jan. 21, the union hasrejected five offers from Shell.
The union is seeking annual pay increases of 6 percent,double the size of those in the last agreement. It also wantswork that has been given in the past to non-union contractors tostart going to USW members, a tighter policy to preventworkplace fatigue and reductions in members' out-of-pocketpayments for healthcare.
The USW has also said the issues directly affect the safetyof refinery workers.
While acknowledging that upstream businesses have been hurt,labor leaders say independent refiners and the refining units ofintegrated companies have been posting big profits thanks tocheap prices for U.S. crudes they turn into gasoline and diesel.
The walkouts are in support of a nationwide pact that wouldcover 30,000 workers and mark the industry's first big strikesince 1980.
Most of the affected refineries are being run near normal by managers, retirees and others from non-union plants brought into replace workers.
"We were very well prepared," Heminger said on a resultscall. "We would expect to have very strong operations."
One plant owned by Tesoro Corp was shutting down dueto maintenance work already under way.
While refiners are promising little or no disruption toproduction, wholesalers and others have snapped up supplies.
The strike helped lift gasoline futures early in theweek, though prices were down about 6 percent on Wednesday below$1.51 a gallon. (Additional reporting by Jessica Resnick-Ault in New York andKristen Hays in Houston; Writing by Terry Wade; Editing by AldenBentley and Alan Raybould)